Commit 6139f2b647cd7b432da3877714befbbf7515e607
2022-11-06T13:12:47
[bdf, pfr, psnames] Accelarate charmap searches. The binary searches within charmaps can be accelerated because they often contain dense continuous blocks of character codes. Within such blocks, you can predict matches based on misses. This method has been deployed in `bdf` since 0f122fef34; we only refactor it there. We now use it in `pfr` and `psnames`, which speeds up the unicode charmap access by about 50% in PFR and Type 1 fonts. * src/bdf/bdfdrivr.c (bdf_cmap_char_{index,next}): Refactor. * src/pfr/pfrcmap.c (pfr_cmap_char_{index,next}): Predict `mid` based on the mismatch distance. * src/psnames/psmodule.c (ps_unicodes_char_{index,next}): Ditto.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228
diff --git a/src/bdf/bdfdrivr.c b/src/bdf/bdfdrivr.c
index eb73a7c..d7e8e0e 100644
--- a/src/bdf/bdfdrivr.c
+++ b/src/bdf/bdfdrivr.c
@@ -92,24 +92,18 @@ THE SOFTWARE.
{
BDF_CMap cmap = (BDF_CMap)bdfcmap;
BDF_encoding_el* encodings = cmap->encodings;
- FT_ULong min, max, mid; /* num_encodings */
FT_UShort result = 0; /* encodings->glyph */
+ FT_ULong min = 0;
+ FT_ULong max = cmap->num_encodings;
+ FT_ULong mid = ( min + max ) >> 1;
- min = 0;
- max = cmap->num_encodings;
- mid = ( min + max ) >> 1;
while ( min < max )
{
- FT_ULong code;
+ FT_ULong code = encodings[mid].enc;
- if ( mid >= max || mid < min )
- mid = ( min + max ) >> 1;
-
- code = encodings[mid].enc;
-
if ( charcode == code )
{
/* increase glyph index by 1 -- */
@@ -123,8 +117,10 @@ THE SOFTWARE.
else
min = mid + 1;
- /* prediction in a continuous block */
+ /* reasonable prediction in a continuous block */
mid += charcode - code;
+ if ( mid >= max || mid < min )
+ mid = ( min + max ) >> 1;
}
return result;
@@ -137,25 +133,19 @@ THE SOFTWARE.
{
BDF_CMap cmap = (BDF_CMap)bdfcmap;
BDF_encoding_el* encodings = cmap->encodings;
- FT_ULong min, max, mid; /* num_encodings */
FT_UShort result = 0; /* encodings->glyph */
FT_ULong charcode = *acharcode + 1;
+ FT_ULong min = 0;
+ FT_ULong max = cmap->num_encodings;
+ FT_ULong mid = ( min + max ) >> 1;
- min = 0;
- max = cmap->num_encodings;
- mid = ( min + max ) >> 1;
while ( min < max )
{
- FT_ULong code; /* same as BDF_encoding_el.enc */
+ FT_ULong code = encodings[mid].enc;
- if ( mid >= max || mid < min )
- mid = ( min + max ) >> 1;
-
- code = encodings[mid].enc;
-
if ( charcode == code )
{
/* increase glyph index by 1 -- */
@@ -171,6 +161,8 @@ THE SOFTWARE.
/* prediction in a continuous block */
mid += charcode - code;
+ if ( mid >= max || mid < min )
+ mid = ( min + max ) >> 1;
}
charcode = 0;
diff --git a/src/pfr/pfrcmap.c b/src/pfr/pfrcmap.c
index 6fa2417..0dd0e23 100644
--- a/src/pfr/pfrcmap.c
+++ b/src/pfr/pfrcmap.c
@@ -69,17 +69,14 @@
pfr_cmap_char_index( PFR_CMap cmap,
FT_UInt32 char_code )
{
- FT_UInt min = 0;
- FT_UInt max = cmap->num_chars;
+ FT_UInt min = 0;
+ FT_UInt max = cmap->num_chars;
+ FT_UInt mid = min + ( max - min ) / 2;
+ PFR_Char gchar;
while ( min < max )
{
- PFR_Char gchar;
- FT_UInt mid;
-
-
- mid = min + ( max - min ) / 2;
gchar = cmap->chars + mid;
if ( gchar->char_code == char_code )
@@ -89,6 +86,11 @@
min = mid + 1;
else
max = mid;
+
+ /* reasonable prediction in a continuous block */
+ mid += char_code - gchar->char_code;
+ if ( mid >= max || mid < min )
+ mid = min + ( max - min ) / 2;
}
return 0;
}
@@ -106,13 +108,12 @@
{
FT_UInt min = 0;
FT_UInt max = cmap->num_chars;
- FT_UInt mid;
+ FT_UInt mid = min + ( max - min ) / 2;
PFR_Char gchar;
while ( min < max )
{
- mid = min + ( ( max - min ) >> 1 );
gchar = cmap->chars + mid;
if ( gchar->char_code == char_code )
@@ -132,6 +133,11 @@
min = mid + 1;
else
max = mid;
+
+ /* reasonable prediction in a continuous block */
+ mid += char_code - gchar->char_code;
+ if ( mid >= max || mid < min )
+ mid = min + ( max - min ) / 2;
}
/* we didn't find it, but we have a pair just above it */
diff --git a/src/psnames/psmodule.c b/src/psnames/psmodule.c
index e7d51e9..4730d8b 100644
--- a/src/psnames/psmodule.c
+++ b/src/psnames/psmodule.c
@@ -412,21 +412,18 @@
ps_unicodes_char_index( PS_Unicodes table,
FT_UInt32 unicode )
{
- PS_UniMap *min, *max, *mid, *result = NULL;
+ PS_UniMap *result = NULL;
+ PS_UniMap *min = table->maps;
+ PS_UniMap *max = min + table->num_maps;
+ PS_UniMap *mid = min + ( ( max - min ) >> 1 );
/* Perform a binary search on the table. */
-
- min = table->maps;
- max = min + table->num_maps - 1;
-
- while ( min <= max )
+ while ( min < max )
{
FT_UInt32 base_glyph;
- mid = min + ( ( max - min ) >> 1 );
-
if ( mid->unicode == unicode )
{
result = mid;
@@ -438,13 +435,15 @@
if ( base_glyph == unicode )
result = mid; /* remember match but continue search for base glyph */
- if ( min == max )
- break;
-
if ( base_glyph < unicode )
min = mid + 1;
else
- max = mid - 1;
+ max = mid;
+
+ /* reasonable prediction in a continuous block */
+ mid += unicode - base_glyph;
+ if ( mid >= max || mid < min )
+ mid = min + ( ( max - min ) >> 1 );
}
if ( result )
@@ -465,14 +464,13 @@
{
FT_UInt min = 0;
FT_UInt max = table->num_maps;
- FT_UInt mid;
+ FT_UInt mid = min + ( ( max - min ) >> 1 );
PS_UniMap* map;
FT_UInt32 base_glyph;
while ( min < max )
{
- mid = min + ( ( max - min ) >> 1 );
map = table->maps + mid;
if ( map->unicode == char_code )
@@ -490,6 +488,11 @@
min = mid + 1;
else
max = mid;
+
+ /* reasonable prediction in a continuous block */
+ mid += char_code - base_glyph;
+ if ( mid >= max || mid < min )
+ mid = min + ( max - min ) / 2;
}
if ( result )